The use of bindings which are impregnated with gypsum as reinforcing bandage material is known. These gypsum bandages do not turn yellow, but they are undesirably heavy, are not very permeable to air, lose strength quickly in moist conditions, for example, during the action of water on the cured bandage, prevent X-ray photographs from being diagnosed owing to the X-ray absorption and scattering thereof and often give rise to skin irritations which are brought about by the growth of bacteria or fungi in the bandage owing to the poor resistance to water thereof.
There have therefore been a large number of attempts to provide bandage materials which do not suffer from these disadvantages. Thus, for example, attempts have been made to impregnate bandage material with polymer solution which may be cured by ultra-violet light and to cure the bandage produced from them by irradiating them with an ultra-violet lamp (Clinical Orthopaedics and Related Research 103, 109-117 (1974)). The operation with ultra-violet sources is complicated. Moreover, the ultra-violet light only reaches the upper layers of the bandage so that curing does not take place or demands a longer time in the deeper layers. Another serious disadvantage of this process lies in the fact that it is not possible to observe the site of fracture by X-ray control during the operation of curing by ultra-violet irradiation. Fast curing bindings based on polyurethane reactive systems and the use thereof for medical support bandages are described in German Offenlegungsschrift No. 2,651,089.
The bandages mentioned therein are usually dyed either by the reactive binding coating itself or by pigments or dyes used in the coating material. Colorless bindings may also be obtained by suitable choice of the starting components (for example, according to Example 12 of German Offenlegungsschrift No. 2,651,089), but they tend to turn yellow owing to the aromatic groups contained in the impregnation. These bandages therefore become unsightly after a very short period. As shown in Example 16 of German Offenlegungsschrift No. 2,651,089, the use of non-yellowing coating material leads to curing times which are unsuitably long for the desired application.
The present invention accordingly provides weather-resistant, substantially non-yellowing support bandages for medical or veterinary use, which no longer exhibit the disadvantages of the above-mentioned prior art materials. The support bandages according to the present invention have, in addition to the advantages mentioned in German Offenlegungsschrift No. 2,651,089, the further advantage of adequate stability to weather and light.